Protective materials that protect against toxic chemicals have commonly been comprised of layered fabrics. Selected layers of the material are designed to adsorb, absorb, detoxify or react with noxious or toxic vapors, and thereby serve as a "vapor barrier". These layers are typically air permeable. Other layers are designed to prevent passage of harmful liquids, and typically are positioned over the vapor barrier to prevent direct contact of liquid with the adsorbent material. Some such "liquid barriers" are air permeable fabrics which have been treated with repellent finishes. Such systems lack in that they will allow aerosols and particulates to pass through, and with minimum pressure, liquids will pass.
Other air impermeable "liquid barriers" provide adequate liquid protection but are water vapor-impermeable or have limited water vapor-permeability. This they do not "breathe", i.e. allow passage of water vapor and thus, are uncomfortable to the wearer.
A two-layer system containing a water vapor-permeable liquid barrier is described in PCT Application 82/00060 (Publication No. WO 83/02066).
Given that multiple clothing layers are used to provide the liquid and vapor protection, this inherently induces heat stress based on the air layers created. It would be desirable to prepare a protective material for clothing that permits passage of water vapor, such as that built up from perspiration, yet effectively does not allow penetration of noxious gases or liquids, all in one composite. It would further be desirable that the system be launderable.
A water vapor conducting fabric laminates that contains fillers which adsorb toxic chemicals is described in U.S. Pat. No. 4,454,191. However, laminates such as those are limited in the amount of filler that can be incorporated or in that the filler becomes contaminated from the material in which it is contained; both limiting the chemical protection provided.
Systems incorporating lamination of liquid and vapor barriers are described in European Patent 0260841. These systems are limited when the adsorbent system is non-launderable such as is typically the case of non-woven, and foam based systems, which in turn, render the composite non-launderable.
Systems which utilize attachment of carbon spheres onto the liquid barrier surface as described in U.S. Pat. No. 4,554,198 offer good chemical protection but suffer in that the spheres are easily dislodged from the surface. Furthermore, unless special precaution is taken, the solid spheres tend to penetrate the liquid barrier layer disrupting the layer and destroying the barrier properties it was meant to provide.